To develop product portfolios and affective design we need to understand the diversity in user needs. The challenge is how to predict what users want and how they will behave. One approach is to understand user emotions and affective needs, and predict successful product design that can match the needs. This paper discusses affect and its link to cognition. To provide a context, several theories are presented. A framework is described that incorporates characteristics of users, tasks, products, and use environment. The goal is to highlight the importance of emotions in enhancing the value of products. This research field, which we call Hedonomics, is new. There are many challenges in developing valid and reliable measurements of affect, which can influence human factors research as well as design.